﻿#pragma once

#include <string>
#include <assert.h>

class Octets {
public:
	// Create an empty slice.
	Octets() : data_(""), size_(0) { }

	// Create a slice that refers to d[0,n-1].
	Octets(const char* d, size_t n) : data_(d), size_(n) { }

	// Create a slice that refers to the contents of "s"
	Octets(const std::string& s) : data_(s.data()), size_(s.size()) { }

	// Create a slice that refers to s[0,strlen(s)-1]
	Octets(const char* s) : data_(s), size_(strlen(s)) { }

	// Return a pointer to the beginning of the referenced data
	const char* data() const { return data_; }

	// Return the length (in bytes) of the referenced data
	size_t size() const { return size_; }

	// Return true iff the length of the referenced data is zero
	bool empty() const { return size_ == 0; }

	// Return the ith byte in the referenced data.
	// REQUIRES: n < size()
	char operator[](size_t n) const {
		assert(n < size());
		return data_[n];
	}

	// Change this slice to refer to an empty array
	void clear() { data_ = ""; size_ = 0; }

	// Drop the first "n" bytes from this slice.
	void remove_prefix(size_t n) {
		assert(n <= size());
		data_ += n;
		size_ -= n;
	}

	// Return a string that contains the copy of the referenced data.
	std::string ToString() const { return std::string(data_, size_); }

	// Three-way comparison.  Returns value:
	//   <  0 iff "*this" <  "b",
	//   == 0 iff "*this" == "b",
	//   >  0 iff "*this" >  "b"
	int compare(const Octets& b) const;

	// Return true iff "x" is a prefix of "*this"
	bool starts_with(const Octets& x) const {
		return ((size_ >= x.size_) &&
			(memcmp(data_, x.data_, x.size_) == 0));
	}

private:
	const char* data_;
	size_t size_;

	// Intentionally copyable
};



inline bool operator==(const Octets& x, const Octets& y) {
	return ((x.size() == y.size()) &&
		(memcmp(x.data(), y.data(), x.size()) == 0));
}

inline bool operator!=(const Octets& x, const Octets& y) {
	return !(x == y);
}

inline int Octets::compare(const Octets& b) const {
	const int min_len = (size_ < b.size_) ? size_ : b.size_;
	int r = memcmp(data_, b.data_, min_len);
	if (r == 0) {
		if (size_ < b.size_) r = -1;
		else if (size_ > b.size_) r = +1;
	}
	return r;
}